History access for end-to-end (E2E) secure content

ChangeBridge: Patent Grants - Networking (H04L)

Published April 7th, 2026

Detected April 8th, 2026

Summary

USPTO granted Patent No. US12598061B2 to Cisco Technology Inc. for a method enabling secure access to historical cryptographic keys by new joiners to encrypted conversations. The invention uses an encrypted skip list that can be stored on untrusted servers, providing logarithmic complexity random access and log-scale overhead for linear access to conversation content.

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What changed

USPTO granted Cisco Technology Inc. Patent No. US12598061B2 on April 7, 2026. The patent covers a system for providing new conversation participants secure access to historical cryptographic keys using an encrypted skip list architecture that supports random access with logarithmic complexity while maintaining security on untrusted storage servers.

For technology companies and software developers, this patent represents potential licensing opportunities or considerations around end-to-end encryption key management solutions. Organizations developing secure messaging or collaboration platforms may need to evaluate whether their systems could implicate this patent's claims related to historical key access and encrypted skip list implementations.

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Source document (simplified)

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History access for end-to-end (E2E) secure content

Grant US12598061B2 Kind: B2 Apr 07, 2026

Assignee

CISCO TECHNOLOGY, INC.

Inventors

Richard Lee Barnes, Brian Christopher Powell

Abstract

An embodiment provides new joiners to a conversation with access to historical keys using an encrypted skip list that can be safely stored on untrusted servers. This list provides random access to conversation content with logarithmic complexity (queries and data size), and imposes small (log-scale) overhead on linear/full access to the conversation content.